Module 3 Flashcards
Identify signs of a chemical change
Signs of Chemical Change:
- Evolution of a gas
- Formation of a precipitate
- Colour change
- Significant temperature change
- Production of an odour
- Dissolution of a solid
Define synthesis
Synthesis is when at least 2 substances combine to form a new substance
Define decomposition
Decomposition is when a reactant is broken down into at least 2 products
Identify forms of decomposition
Forms of Decomposition:
- Thermal decomposition – heat energy
- Electrolysis – electrical energy
- Decomposition by light energy
Define combustion
Combustion is the process of burning a fuel - usually a hydrocarbon - in the presence of oxygen, releasing thermal energy
Identify the chemical equation of combustion
Chemical Equation of Combustion: Hydrocarbon + Oxygen Gas → Carbon Dioxide + Water
Define complete combustion
Complete Combustion occurs when oxygen is plentiful and produces carbon dioxide
Define incomplete combustion
Incomplete Combustion occurs when oxygen is limited and produces carbon monoxide
True or False. When the amount of oxygen is less than 50% of the required amount for the reaction to combust completely, methane can be produced from larger hydrocarbons
True
Define precipitation reaction
Precipitation Reaction is the process of mixing 2 transparent ionic solutions to form a precipitate
Define spectator ions
Spectator Ions are ions that are not involved in the formation of a precipitate – eliminated in net ionic equations – aqueous for reactants and products
Neutral Species Equation →…
Neutral Species Equation → Complete Ionic Equation → Net Ionic Equation
Define the SNAAP Rule
SNAAP Rule – All of the initials are soluble; never form a precipitate
- Sodium
- Nitrate
- Ammonium
- Acetate
- Potassium
Define neutralisation equation
Neutralisation Reaction is a reaction between an acid and base of equal magnitude on the pH scale
Identify the chemical equation for neutralisation
Acid + Base → Salt + Water
Identify the chemical equations for acid + metal carbonate
Acid + Metal Carbonate → Salt + Water + Carbon Dioxide
Acid + Metal Hydrogen Carbonate → Salt + Water + Carbon Dioxide
Identify the chemical name for limewater
Calcium Hydroxide
Define limewater test
Limewater Test detects the presence of carbon dioxide gas
Define pop test
Pop Test detects the presence of hydrogen gas
Identify a toxic food source for the Indigenous population
The fruit of the cycad
Outline the process of how the Indigenous population removed the toxins from the cycad
The poison within the fruit was removed through:
- Leaching: The kernels are cut open, grounded, and soaked in water – the toxins are soluble in water
- Fermentation: The kernels are stored in a moist environment for months till fermentation
- Straining: The kernels are put in dilly bags and placed over running water to strain the toxins
- Heated and Dried: Increases solubility of toxins and denatures toxic proteins
Identify the chemical reaction for metal + water
Metal + Water → Metal oxide + Hydrogen Gas
Identify the chemical reaction for metal + aqueous acid
Metal + (Dilute) Acid → Salt + Hydrogen Gas
Outline when metal and metal ions react
Metal only reacts with metal ions if the metal is more reactive, displacing the ions
Define activity series of metals
Activity Series of Metals is a ranking of reactivity of metals in a descending order
The reactivity of metals can be explained by which periodic trends?
Interdependence of Reactivity of Metals and Trends within the Periodic Table:
- Atomic Radius
- Ionisation energy
- Electronegativity
Define redox reaction
Redox Reaction is a reaction where oxidation and reduction occurs simultaneously in each individual half equation – involves the transfer of electrons
Define oxidising agent
Oxidising Agent is a chemical that oxidises other chemicals; itself is reduced
Define reducing agent
Reducing Agent is a chemical that reduces other chemicals; itself is oxidised
Identify the rules of oxidation number
Rules of Oxidation Number:
- The oxidation number of an element is zero
- The oxidation number of a simple ion is the charge
- Hydrogen has an oxidation number of +1 when it forms compounds with non-metals except in metal hydrides – the oxidation number of hydrogen is −1
- Oxygen usually has an oxidation number of −2 except in compounds with fluorine, where oxygen has a positive oxidation number. In peroxides, oxygen has an oxidation number of −1
- The sum of the oxidation numbers in a neutral compound is zero
Define galvanic cell
Galvanic Cell is a type of electrochemical cell in which chemical energy is converted into electrical energy
Define anode
Anode is the electrode where oxidation occurs at the anode; electrons leave the electrode
Define cathode
Cathode is the electrode where reduction occurs at the cathode; electrons enter the electrode
Identify the purpose of the salt bridge
The salt bridge – internal circuit – maintains electrical neutrality by:
- Cations from the salt bridge move towards the cathode
- Anions from the salt bridge move towards the anode
Calculate the voltage produced by a galvanic cell
The voltage (E0) = E0 of the cathode - E0 of the anode
State the collision theory
Collision Theory states for a reaction to occur, the reactant particles must:
- Make contact (collide) with each other
- Collide with sufficient energy to break bonds within the reactants
- Collide with the correct orientation to break the bonds within the reactants to allow the formation of new products
Define activation energy
Activation Energy is the minimum energy that a collision must possess for a reaction to occur
Calculate the rate of reaction
Rate of Reaction = ΔConcentration / Time
Outline the factors for the rate of reaction
The rate of reaction is affected by:
- Temperature – increases the proportion of molecules that have energy exceeding the activation energy
- Surface Area – increases the exposed area for collisions
- Concentration – increases the amount of molecules
- Use of a catalyst – reduces the activation energy
Define enthalpy
Enthalpy (ΔH) is the total energy possessed by a substance
